Routing and switch cases

Many uses of a query builder aren't one filter but a list of them: route a form response to the first matching team, pick a price tier, assign a support queue. That's RAQB's "ternary mode" and SQL's CASE WHEN.

import { compileCases, type CasesOf } from '@qnot/core';

const routes: CasesOf<typeof fields, { team: string }> = {
  cases: [
    { label: 'Enterprise', when: enterpriseQuery, then: { team: 'sales' } },
    { label: 'EMEA', when: emeaQuery, then: { team: 'emea-support' } },
  ],
  otherwise: { team: 'self-serve' },
};

const route = compileCases(fields, routes);
route(response); // { value: { team: 'emea-support' }, index: 1 }

index is the matching case, or -1 when otherwise was used.

Editing routes

Each route's condition is an ordinary query, so give each one its own store and builder. A routing form editor is a list of cards, each holding a QueryBuilder (or your own UI over the hooks), a result picker, and controls to reorder and duplicate routes. A common touch is an "all / any / none of these rules" switch, which maps to AND, OR and NOT+OR on the group.

Exporting

encodeCases exports the whole switch with codecs that support it:

import { encodeCases } from '@qnot/core';
import { sqlFormat } from '@qnot/core/formats/sql';

encodeCases(sqlFormat({ dialect: 'postgres' }), { cases: routes.cases.map((c) => ({ when: c.when, then: c.then.team })), otherwise: 'self-serve' }, fields);
// CASE WHEN … THEN 'sales' WHEN … THEN 'emea-support' ELSE 'self-serve' END

SQL gives CASE WHEN, JsonLogic an if chain, MongoDB $switch, SpEL nested ternaries and text a sentence. Elasticsearch and the UI-state codecs don't support cases.